Le Tung B K, Stevenson Clare E M, Buttner Mark J, Lawson David M
Department of Molecular Microbiology, John Innes Centre, Norwich NR4 7UH, England.
Acta Crystallogr Sect F Struct Biol Cryst Commun. 2011 Mar 1;67(Pt 3):307-9. doi: 10.1107/S1744309110053078. Epub 2011 Feb 18.
Crystals of SimR were grown by vapour diffusion. The protein crystallized with trigonal symmetry and X-ray data were recorded to a resolution of 2.3 Å from a single crystal at the synchrotron. SimR belongs to the TetR family of bacterial transcriptional regulators. In the absence of the antibiotic simocyclinone, SimR represses the transcription of a divergently transcribed gene encoding the simocyclinone efflux pump SimX in Streptomyces antibioticus by binding to operators in the simR-simX intergenic region. Simocyclinone binding causes SimR to dissociate from its operators, leading to expression of the SimX efflux pump. Thus, SimR represents an intimate link between the biosynthesis of simocyclinone and its export, which may also provide the mechanism of self-resistance to the antibiotic in the producer strain.
通过气相扩散法培养了SimR晶体。该蛋白质结晶为三方对称，在同步加速器上从一块单晶记录到了分辨率为2.3 Å的X射线数据。SimR属于细菌转录调节因子的TetR家族。在没有抗生素西莫环素的情况下，SimR通过与天蓝色链霉菌中simR-simX基因间区域的操纵子结合，抑制一个反向转录的基因的转录，该基因编码西莫环素外排泵SimX。西莫环素的结合导致SimR与其操纵子解离，从而导致SimX外排泵的表达。因此，SimR代表了西莫环素生物合成与其输出之间的紧密联系，这也可能是产生菌对抗生素自身抗性的机制。
